Gender differences in clinical, laboratory and polysomnographic features of restless legs syndrome

Restless legs syndrome is a common neurological disorder with a clear female predominance. This study aims to evaluate gender differences in clinical, laboratory and polysomnographic features in patients with restless legs syndrome. For this retrospective analysis, 42 women and 42 men from the Innsbruck RLS database matched by age and therapy were included. Demographic data as well as different severity scales (IRLS, RLS-6 and CGI) were evaluated. Laboratory parameters included several indicators of serum iron status. In all patients, polysomnography was performed according to the AASM guidelines, and periodic leg movements during sleep were scored according to the AASM criteria. IRLS, RLS-6 and CGI revealed more severe symptoms in women (IRLS median [range]: 17.5 [0-35] versus 13.5 [0-32], p = 0.028; RLS-6 median [range]: 18 [0-39] versus 12 [1-42], p = 0.014). Women had lower serum ferritin levels than men (median [range] in microg L^-1 : 74 [9-346] versus 167 [15-389], p < 0.001). Twenty-two women and eight men (53.7% versus 22.2%, p = 0.003) had ferritin values below 75 microg L^-1 . Periodic leg movements during sleep indices were significantly lower in women than in men (median [range] in number per hr: 11.4 [0-62.5] versus 40 [0-154], p = 0.004, and 12.6 [0-58.5] versus 40 [0.5-208], p = 0.002, for night I and night II, respectively). Restless legs syndrome severity as measured by validated scales was worse in women, while periodic leg movements during sleep indices were higher in men. These results suggest a possible gender difference in phenotypical presentation of restless legs syndrome, manifesting with predominantly sensory symptoms in women and predominantly motor symptoms in men.